Heat exchanger



Sept. 23, 1952 o, A LABUs 2,611,584

HEAT EXCHANGER Filed March 22,, 1947 INVENTOR. F1 5 a Patented Sept. 23, 1952 HEAT EXCHANGE Otto A.Labus, La Crosse, Wis., assignor to The Trane Company, La Crosse, Wis.

Application March 22, 1947, Serial No. 736,472

This invention relates to heat exchangers of the type known as tube within a tube.

It is an object of this invention to provide heat exchangers particularly for dissipating latent heat of volatile fluids whereby a high rate of heat transfer per unit of condensing surface is maintained by rapidly and continuously scavenging the condensate from thecondensing surface of such'heat exchangers. Another object of the invention is to provide a heat exchanger which maintains uniform heat dissipating performance over its entire face even though the heat exchanger is of considerable length.

It is recognized that tube within a tube heat exchangers having the steam supply and the condensate outlet at the same end or opposite ends and with the inner tube (commonly known as the distributing tube) containing a plurality of small openings in its wall for steam distribution are old in the art.

,Heat exchangers prior 'to-this'invention have.

is therefore materially reduced. The accumulation of condensate also has the effect of creating a non-uniform heat dissipating rate along the length of the tubes. This effect is particularly serious when the tubes are long and the annular space between the tubes is small. v

4 Claims. (01. 257-60) Among other advantages of this invention is that a tube within a tube heat exchanger with openings as disclosed herein, canbe constructed of considerable length, having a combination of tube sizes of relatively close diameters, thus permitting the use of smaller outer tubes.

Another advantageof this invention is that it provides a high condensing rate when the tube within a tube heat exchanger, is designed for .use of extended surface on the outer. tube which a 2 exchanger is employed in connection with a low head of steam supply and low temperature fluids in heat exchange relationship therewith.

Referring to the drawing, Figure 1 is an elevation partly in cross-section of a same end connection heat exchanger with extended surface embodying this invention.

Figure 2 is an elevation partly in cross-section of an opposite end connection heat exchanger.

Figure 3 is a cross-sectionalview of the tube within a tube combination taken on line 3- 3 of Fig. 2.

Referring to Figure l, which shows a heat exchanger with a same endconnection; the-numeral l represents a manifold with a steam inlet passageway 2 connected to the steam chest 3 which is separated by a partition wall 5 from the condensate receiver 6 which has an outlet passageway 1. The foregoing forms a complete steam supply and condensate return manifold;

Heat exchange fluid in the form of steam flows through the steam conductor 8, from the steam chest 3, and is interiorly positioned within an outer tube H! which has attached to it fins 26.

The conductor tube 8, as shown in Fig. l, is open at its end remote from said steam chest 3 and is provided with'a'plurality of directional fiow jet like openingsall which are spaced and disposed along the walls of the conductor tube 8 to cause a directional fluid flow in relation to the longitudinal steam flow in the conductor tube 8, thereby causing an acceleration of the flow of condensate which may accumulate in the annular space it between the conductor tube 8 and the outer tube [0.

In Figure 1 the directional flow is reverse to the normal longitudinal steam flow. The resultant rapid scavenging of the condensate results in maintaining the maximum condensing surface available, for high heat transfer through the outer tube 10, since the coefficient of heat transfer in the condensing phase is many times greater than the transfer in the liquid phase, particularly for liquid in the static state.

From thi description it is obvious that this arrangement eliminates opposing flow forces of volatile fluids with relation to the normal flow of condensate in the annular space H, and acts to aid in quickly scavenging the condensate thus imparting acceleration to the flow of condensate to the condensate receiver wherebyhigh rate ofcondensation may be successfully handled in relatively small annular spaces I l between inner and outer tubes.

The outer tube Ill is connected to'the condensate receiver wall [2, its opposite end i sealed,

tubes are welded into the at [3. Extended outer heat transfer surface 26 may be integrally formed with the outer tube or may be in the form of separate fins fixed to the outer tube which are desirable for high rate heat transfer from steam to air or from any volatile refrigerant fluid to air.

Referring to Figure 2, which illustrates an opposite end connection type heat exchanger, it represents a steam supply header with an inlet passageway l5, and represents 'a' condensate receiver with an outlet 2|. The outer tube It! is attached to both the supply header and the condensate receiver and has an opening into the condensate receiver. The inner conductor tubes 8 are shown enlarged at the inlet end 22- which are fastened to the outer tube Hi to form'- a tight joint between the inner tube band the outer tube [0, which may be welded, brazed or' otherwise tightly connected. The condensate receiver 28 is connected vto the outer tube It) for the how of condensate from'the annularspace between the inner tube-8 andthe, outer tube it. There are directional fiowjet-like openings 9 in this construction disposed-along the inner tube 8 having their outlet passageway :fixed in the. direction of the normal path of the condensate which may collect in the annular space ll be tween the inner and outer tube. The inner tube 8 has its opposite end sealed at 25, ;.T,he outer condensate receiver at 24.

From the foregoing description it is obvious that any condensable fluid under pressure supplied to the inner tube 87Wi11 flow through the directional flow jet like openings 9 into the annular space H and form cohdensateby reason of the heat exchange of the outer tube surface. The condensate will tend to collect in the bottom of the tube in the annular space I i and will have its flow or drainage to the condensate receiver 28 accelerated because the-directed flow of the heat exchange fluid through the opening 8 will cause the steam to'flow in a parallel .direction to the normal flow vof the condensate,

thereby maintaining .a maximum heat transfer.

surface of the outer tube.

The opening 9, as shown in Figure 3, is positioned between the conducting tube 8 and the outer tube 10 and is made by cutting the tube 8, or making a slot therein, and bending a portion of the tube radially away from the tube to form a nodule 21, which on one side has an inclined portion 28. The periphery of the'nodule 2'l is represented by the numeral 15 and said periphery contacts the inner portion of the tube vH3. The other side of the nodule has an opening 9, the axis of which extends in the direction of one end of the tube so that it can be said that the opening 9 faces one end of the tube whereby steam emitting therefrom will tend to flow in the direction of one end 'ofithe tube. The same result may be obtained by indenting a portion of the tube, in which case the opening will still face toward one end of the tube and cause steam to flow in that direction. I

Referring to Figure 2, the tube i0 is positioned into the outlet header 2 0 at 24 and to the inlet header I4 at H. p I j Referring to Figure 1,, the tube 10 is positioned into the portion of the header 12 at 23 while the distributing tube is positioned into the wall 5 at L8. a l

Having thus described my invention what I claim is:

1. A heat exchanger comprising a condensate 4 chamber, a gas chamber, a series of condensing tubes communicating at one end with said condensate chamber, a series of gas distributing tubes communicating at one end with said gas chamber and being positioned within said condensing tubes and forming a passageway therebetween, the tubes of one of said series being open at their extremities whichare remote from said gas chamber thetubes of the other of said series being closed at their ends which are remote from said gas chamber, a plurality of orifices spaced along the gas distributing tubes, said orifices having discharge openings facing substantially in the direction of the length of the tubes and in the direction of the condensate chamber whereby the gas is discharged from the distributor tubes substantially in the direction of the length of the tubes and in the direction of the condensate chamber.

2. A heat exchanger comprising, a gas chamber, a series of gas distributing tubes communicating with said gas chamber for flow of gas from said gas chamber, a condensate chamber, a series of condensing tubes communicating with said condensate chamber, each of said condensing tubes surrounding one of said gas distributing tubes, each of said condensing tubes being of such a size as to form a passageway for flow of gas and condensate between the outside of the gas distributing tube and the inside of the condensing tube, the tubes of one of said series being open at their extremities which are remote from said gas chamber, the tubes of the other of said series being closed at their ends which are remote from said gas chamber, said gas distributing tubes having a plurality of orifices spaced along their lengths for the discharge of gas from said distributing tubes to said condensing tubes, said orifices being constructed to provide passageways, the discharge portions of which have axes which extend at a substantial angle with respect to a line normal to the axes of said tubes and with the opening of said discharge portion facing in the direction of said condensate chamber to discharge gas whereby the gas flows therefrom substantially in the direction of the length of the tubes and toward said condensate chamber.

3. A heat exchanger comprising a header having a supply chamber and a return chamber, a plurality of tubes closed at one end and communicating at the other end with said return chamber of said header, a plurality of distributing tubes positioned within said first mentioned tubes to form a passageway therebetween, said distributing tubes being open at one extremity and extending at the other extremity through said return chamber and communicating with said supply chamber to receive fluid from said supply chamber, said distributing tubes having a plurality of orifices spaced along their lengths, said orifices having discharge openings facing substantially in the direction of the return chamher to discharge fluid in a direction substantially parallelto the tubes.

4. A heat exchanger comprising a s pply header and a return header, a plurality of tubes fastoned at one end to said supply header and at the other end communicating with said return header for discharge of fluid thereto, a plurality of distributing tubes within said first mentioned 'tubes and forming passageways therebetween,

means closing the passageway between said first mentioned tubes and said distributing tubes at thesupply header ends of said tubes, means clos openings facing substantially in the direction of the return header so as to discharge fluid from the distributing tubes into said first mentioned tubes in a direction substantially parallel to their axes.

OTTO A. LABUS.

6 REFERENCES CITED The following references are of record in the Number file of this patent: UNITED STATES PATENTS Name Date Jackson Dec. 22, 1931 Harnett Mar. 1, 1932 Ashley Jan. 21, 1941 Polk Mar. 8, 1949 

